Vacuum IG units are known in the art. For example, see U.S. Pat. Nos. 5,664,395, 5,657,607, 5,891,536 and 5,902,652, the disclosures of which are all hereby incorporated herein by reference.
Prior art FIGS. 1-2 illustrate a conventional vacuum IG unit. IG unit 1 includes two spaced apart sheets of glass 2 and 3 which enclose an evacuated or low pressure space 16 therebetween. Glass sheets 2 and 3 are interconnected by peripheral or edge seal of fused solder 4 and an array of support pillars 5.
Pump out tube 8 is sealed by solder glass 9 to an aperture or hole which passes from an interior surface of glass sheet 2 to the bottom of recess 11. A vacuum is attached to tube 8 (prior to the tube being sealed) so that the interior space 16 between sheets 2 and 3 can be evacuated to create a low pressure area. After evacuation, an end of tube 8 is melted to seal the vacuum in space 16.
As illustrated in FIGS. 1-2, spacers or pillars 5 are typically provided between the glass sheets 2 and 3 in the viewing area of the unit. As discussed in U.S. Pat. No. 5,664,395, these spacers or pillars may be made of nickel, iron, molybdenum, tungsten, tantalum, titanium, aluminum, steel or stainless alloys. Unfortunately, such metal spacers or pillars are substantially opaque to visible light, and thus may be considered an eyesore (i.e., aesthetically nonpleasing) to those viewing the window because they are scattered throughout the viewing zone.
It is also known to make such spacers or pillars of spherical glass beads, as discussed, for example, in U.S. Pat. No. 4,683,154. Unfortunately, glass bead spacers may be susceptible to breaking or cracking in certain instances and are undesirable for this reason alone.
FIG. 3 is a side cross sectional view of another conventional vacuum IG window unit. This unit differs from that of FIGS. 1-2 in that the glass sheets of FIG. 3 are of different sizes, and edge seal 4 contacts an outer vertically extending periphery of one of the glass sheets. However, this unit suffers from the same problems as the unit of FIGS. 1-2 as the spacers are the same.
It is apparent from the above that there exists a need in the art for a vacuum IG unit including spacers or pillars that are visible unobtrusive, substantially transparent to certain visible wavelengths of light, aesthetically pleasing, and/or of high strength.
This invention will now be described with respect to certain embodiments thereof, accompanied by certain illustrations.
An object of this invention is to provide spacers or pillars that are substantially transparent to certain visible wavelengths of light, for use in a vacuum IG window unit.
Another object of this invention is to provide aesthetically pleasing and high strength spacers or pillars in a vacuum IG window unit.
Another object of this invention is to provide sapphire inclusive spacers or pillars for a vacuum IG window unit.
Another object of this invention is to provide Al2O3 inclusive spacers or pillars for a vacuum IG window unit.
Another object of this invention is to fulfill any and/or all of the above-listed objects and/or needs.
Generally speaking, this invention fulfills any or all of the above described objects or needs in the art by providing a thermally insulating glass panel comprising:
first and second spaced apart glass substrates defining a low pressure space therebetween having a pressure less than atmospheric pressure;
a plurality of spacers disposed between said first and second glass substrates for spacing said substrates from one another in order to maintain said low pressure space therebetween;
a hermetic edge or peripheral seal including at least one sealing material; and
wherein at least some of said spacers include sapphire so as to be substantially transparent to at least certain wavelengths of visible light.
In certain embodiments, at least some of said spacers are transparent to at least about 90% of visible light wavelengths.